Threshold absence and the implementation chasm: equity paradoxes in national English language education policy in Tuyen Quang, Vietnam

National policies that promote English as a second language assume baseline conditions in teaching personnel, infrastructure, digital connectivity, and prior exposure that cannot be taken for granted across subnational contexts. This study examines this problem through Vietnam's Decision No. 2371/QĐ-TTg of 27 October 2025, approving the project “Making English a second language in schools for the 2025–2035 period, with a vision to 2045,” and two official education reports from post-merger Tuyen Quang Province. The analysis maps conditions presupposed by the national policy against those documented locally. It develops the concept of an implementation chasm to describe a structural condition in which standard implementation strategies are insufficient because key preconditions are absent or unevenly distributed. The findings identify interacting constraints in teacher supply, physical and digital infrastructure, and multilingual learner conditions. These constraints reveal an equity paradox in uniform language policy: a common national ambition may produce unequal educational exposure when local ecological readiness differs substantially. The article, therefore, argues for differentiated language planning grounded in ecological readiness rather than uniform administrative timelines.